302 Scott and Brebnen.—On the Anatomy 
Heimerl 1 , and Pax 2 , who have worked at the anatomy of these 
families, appear to have paid no special attention to the 
development- Some of GheorgiefFs figures, however, in PL 
VI and VII of his paper, leave no doubt as to the centripetal 
development of the phloem in the plants he examined. He 
describes and figures obliteration of the phloem here, similar 
to that which we have so often mentioned in Strychnos. 
The phloem-islands of Strychnos , then, in their centripetal 
development from the cambium, conform to a law of wide 
though not of universal application. 
The occurrence of medullary phloem in the root affords one 
more decisive argument that the vascular cylinder of the root 
should no longer be described as a single vascular bundle, 
but should be regarded as corresponding to the whole vascular 
system and pith of the stem. 
The material for our investigation was supplied partly from 
the Royal Gardens at Kew, partly from the Garden of the 
Society of Apothecaries at Chelsea, and to the heads of both 
these institutions we tender our thanks. We wish further to 
thank both the Kew authorities and those of the botanical 
department of the British Museum, for valuable help in the 
identification of species. 
Some of the preparations, including that from which Fig. i 
is drawn, were made by Miss A. L. Smith, whose help we 
have pleasure in acknowledging. 
1 On Nyctagineae in Engler u. Prantl’s Die natiirlichen Pflanzenfamilien, Theil 
III, Abth. i, 1889. 
2 On Aizoaceae. Ibidem. 
